A technology disclosed herein relates to a management method for a storage system, and more particularly to a data backup method in a tape library.
There has been a tendency of increasing amount of data processed by a computer system of a company or the like, which has been accompanied by an increasing amount of backup data used to prevent a data loss caused by a failure or the like.
To store a large amount of data at low cost, a tiered storage system is generally used. In the tiered storage system, frequently accessed data is stored in a relatively expensive but high-performance storage medium such as a magnetic disk. On the other hand, infrequently accessed data such as backup data is stored in a relatively inexpensive storage medium such as a magnetic tape.
The process of copying the data stored in the magnetic disk in the magnetic tape to back up the data may affect performance of the magnetic disk device which is a copy source. As a result, performance of another process using the magnetic disk device which is the copy source (e.g., an application process of accessing data in the magnetic disk device) may deteriorate. To prevent such an influence on the performance, a technology which combines data copying between the magnetic disk devices with data copying from the magnetic disk device to a magnetic tape device has been disclosed (JP 2003-140981 A).
According to the technology disclosed therein, two volumes set in the magnetic disk device are mirrored. In other words, when data of one volume (primary volume) is updated, the updated data is copied to the other volume (secondary volume). As a result, the same data is stored in the two volumes. When the data of these volumes is backed up in a magnetic tape, the copying between the two volumes is stopped. While the data of the secondary volume is copied in the magnetic tape, the primary volume permits access from an application. Thus, the data can be backed up without affecting processing performance of the application.
Additionally, a storage system that includes a disk interface for a host computer and a function of storing data of a logical volume in a magnetic tape has been disclosed (JP 2006-163454 A). According to this storage system, management costs can be reduced by managing storage areas of a magnetic disk device and a magnetic tape device as logical volumes.